Man has been extracting valuable compounds from plants throughout human time. These extracts range from medicine to poisons, perfumes to flavorings and many others. In today's modern economy, plant extracts are still highly sought and valuable commodities.
One of the main extraction methods existing today is solvent-based extraction in which the plant material containing the extractable compounds is bathed or washed in a solvent. The solvent uptakes the extractable compounds from the plant material and combines the plant material in a solution with the solvent. The compound solution is then purified to remove the solvent and recover the desired extracted compound(s). Often, the purification process involves heating the solution to “boil off” or volatilize the solvent from the solution, leaving the extracted compound(s) behind. Such extraction methods usually use a solvent having a lower boiling point than that of the products so that the solvent can be boiled off without removing or damaging the extracted compound(s).
Typically, the solvents used in such extraction processes are hydrocarbon-based or an alcohol, both of which have low boiling points, but can be explosive or flammable when volatilized. The explosive and flammable nature of the hydrocarbon-based extract processes has led to many injuries and significant property damage as users try to perform these extraction processes.
Additionally, because the hydrocarbon solvents are easy to boil away, the solvents are oftentimes lost as a vapor to the atmosphere during the extraction and purification processes. The loss of the solvent makes the processes expensive to perform because additional solvent must be added for each new extraction process, which requires a large butane supply.
Some of the main solvent-based plant extract processes include those used to extract essential oils, Napetalactone (the main component of catnip) and various pharmaceutical compounds. Also, the rise of medical marijuana and the legalization of cannabis and cannabis-based products has made cannabis plant extracts a legal and marketable pharmaceutical and recreational commodity. One of the major extracts desired from cannabis plants is hash oil. Hash oil is concentrated cannabinoids that are extracted from the cannabis plant. The main psychoactive component of marijuana is a cannabinoid called tetrahydrocannabinol, better known as THC. Cannabinoids are a class of compounds that act on the cannabinoid receptors of the brain. The interaction of the cannabinoids with the receptors is what causes a user to experience mood-enhancing effects. Marijuana contains a variety of cannabinoids, THC and cannabidiol (CBD) being the major constituents, among many others.
The process of extracting hash oil from cannabis plant material often involves running butane, a hydrocarbon-based solvent, through the plant material or soaking the plant material in butane to wash out the cannabinoids. The cannabinoid-rich solvent solution is then purified, often by heating it, which volatilizes the butane and leaves behind the cannabinoid extract. During the volatilization process, the butane solvent is converted into a gaseous form that is then highly flammable and potentially explosive, which presents a significant danger to personal safety and to any surrounding property.
Currently, to assist with recovery of the solvent from the solvent-extract solution, many cannabinoid extract producers use a pump, often a refrigerant recovery pump, to move the vapors from the extract container to a solvent storage container. The pump compresses the gaseous solvent vapors back into a liquid phase. Often these pumps have a mechanical pumping means, are electrically powered and are generally not food safe. Further, the use of such pumps can be dangerous as the pumps are not designed to handle a flammable hydrocarbon. Solvent vapors can leak from the pump and mix with the surrounding environment where they risk being sparked from either the operation of the pump itself or from other external sources. Additionally, any extract process using the recovered solvent risk being contaminated by pump lubricants or adverse chemical reactions with the pump construction.
Therefore, there exists a need for solvent-based extraction processes that can be performed safely without endangering operators and property. Additionally, there exists a need for a clean solvent conservation process to reduce the cost and increase the efficiency of the extraction process.